For long form video (2mns 30 secs < 10+ mns) , TIMESTAMPS are suggested to be used to help improve your search engine optimization (SEO) ranking on Google.
Timestamps allow you to put SPECIFIC LINKS to moments into your YouTube video so your users can identify them without having to watch the whole video.
Timestamps tell Google what your video is about without ever having to go into YouTube.
The YouTube timestamps IMPROVE USER EXPERIENCE too by making it easier to view the parts that users may be interested in.
By adding a timestamp, you can HELP IMPROVE RETENTION by directing users to the most relevant portion of your video from the outset.
It also maintains attention, especially in longer videos – users can then
QUICKLY FIND AND CLICK ON THE CONTENT THEY’RE SEARCHING FOR.
By clearly providing the content of your video in a short/organized way, your videos will be crawled by the Google SEO bots more quickly and you’ll increase your chances of ranking higher in search results